1. Field of the Invention
Embodiments of the present invention generally relate to processing images pertaining to digital microscopy and, more specifically, to a method and apparatus for improving depth of field (DOF) in microscopy.
2. Description of the Related Art
A digital microscope images a specimen at different depths to create a sequence of digital images. Each image represents a slice of the specimen at a particular depth of focus. Thus, in a single slice of a specimen only a fraction of the entire specimen is in focus. The sequence of digital images is stacked along a Z dimension corresponding to depth, referred to as a Z-stack. Each image in a Z-stack is focused at a different depth in the captured specimen. The optics of digital microscopes impose a very narrow depth of field, too small to capture the entire specimen in focus with a single picture. Thus, all images in the Z-stack are of the same specimen, but with different focus for each image.
Existing methods for improving DOF of images, i.e., extended depth of field (EDOF) images, have a common underlying rationale. In existing methods, the best image for each specified location in an output image is found by identifying the digital image at a depth where the identified digital image gives the best focus at the specified location. As a result, an output pixel in the output image acquires a value based on the best image found. Existing methods differ in defining (i.e. determining) best focus and enhancing consistency in estimating depth-map. However, performance of these methods is often poor and the methods are problematic due to their high computational complexity.
Thus, there is a need for method and apparatus for improving depth of field (DOF) in microscopy.